蓝藻暴发对湖泊生态系统中内源营养盐的影响

发布时间：2017-12-31 10:37

本文关键词：蓝藻暴发对湖泊生态系统中内源营养盐的影响　出处：《南京理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：近几十年来,随着人类活动干扰加剧,湖泊富营养化和蓝藻水华成为全球面临的重大环境问题。在湖泊外源污染得到有效控制的情况下,沉积物内源营养盐的释放是水体持续富营养化、影响治理成效的关键因素。然而,由于缺乏原位技术,很大程度上限制了内源污染的深入研究。本文通过室内模拟蓝藻暴发的条件,利用ZrO-Chelex薄膜扩散梯度(ZrO-ChelexDGT)、微电极技术、Rhizon技术相结合,发展了一种原位测定沉积物有效磷、铁、氮的方法。以典型富营养湖泊太湖梅梁湾为研究对象,利用ZrO-Chelex DGT技术探讨了营养盐在蓝藻暴发阶段的规律。主要结果如下:(1)室内模拟蓝藻暴发的条件,利用微电极等技术原位监测pH、DO、Eh等参数的昼夜变化及阶段性变化,研究在蓝藻水华发生期间对各参数的影响。第1-20天蓝藻不断增长繁殖,随后蓝藻开始降解。白天蓝藻进行光合作用,pH升高(Max=10.53),溶解氧升高(Max=16.0mg/L),晚上呼吸作用大于光合作用,pH降低(Min=7.57),溶解氧降低(Min=2.5mg/L);沉积物中,随着沉积物深度的增加,pH、溶解氧、Eh均呈降低的趋势,但是蓝藻组的下降更快。(2)室内模拟蓝藻暴发的条件,利用ZrO-ChelexDGT等技术原位监测间隙水、沉积物中有效态Fe2+的含量及Fe2+的释放通量,研究蓝藻水华期间对沉积物中铁的影响。上覆水中的Fe2+含量很低,界面下0.5cm间隙水中的Fe2+含量显著增加;蓝藻进行光合作用,pH增加,蓝藻组释放的溶解性Fe2+部分被蓝藻吸收供其生长所需,第5天开始白天蓝藻组的通量显著增加。沉积物有效态Fe2+在上覆水中含量很低,在0-20mm有效态Fe2+逐渐释放,随着深度的增加,有效态Fe2+含量逐渐减小。(3)室内模拟蓝藻暴发的条件,利用ZrO-ChelexDGT等技术原位监测间隙水、沉积物中有效态磷的含量及磷的释放通量,研究蓝藻水华期间沉积物磷的释放机制。白天蓝藻的光合作用增加上覆水中的pH、DO值,夜里pH、DO值降低,OH-的增加促进沉积物中PO4-的释放,加上蓝藻直接对沉积物中P的吸附降低了间隙水中P的浓度,第5天之后,OH-的增加不再促进沉积物中PO4-的释放,沉积物中P的释放主要受到DO以及蓝藻降解的控制。(4)间隙水中硝态氮与氨氮的浓度高于上覆水,存在着由高浓度向低浓度进行的分子扩散作用。上覆水中硝态氮与氨氮的含量的变化趋势是一致的,在第1天至第5天呈下降趋势,第15天显著增加后又逐渐降低。间隙水中溶解性氮的主要存在形式是氨氮,沉积物不同深度间隙水中的硝态氮、氨氮的变化规律是一样,均是先减小再增加。
[Abstract]:In the past several ten years, with the intensification of human activities, lake eutrophication and cyanobacteria Shui Hua have become a major environmental problem in the world. The release of endogenous nutrients from sediments is a key factor in the sustained eutrophication of water and affects the effectiveness of governance. However, due to the lack of in-situ technology. To a great extent, the study of endogenous pollution is limited. In this paper, the ZrO-Chelex membrane diffusion gradient (ZrO-Chelex) was used to simulate the outbreak of cyanobacteria. A method for in situ determination of available phosphorus, iron and nitrogen in sediments was developed by combining microelectrode technique with Rhizon technique. Meiliang Bay of Taihu Lake, a typical eutrophic lake, was used as an object of study. The rule of nutrient salt in the stage of cyanobacteria outbreak was studied by using ZrO-Chelex DGT technique. The main results were as follows: 1) the conditions for simulating the outbreak of cyanobacteria in laboratory. In situ monitoring of diurnal and periodic changes of pH DOA Eh and other parameters by microelectrode technique was used to study the effects of cyanobacteria Shui Hua on the parameters during the development of cyanobacteria Shui Hua. During the 1-20 days, cyanobacteria continued to grow and reproduce. Then the cyanobacteria began to degrade. During the day, the photosynthesis of cyanobacteria increased the pH value of Maxanthus 10.53 and the dissolved oxygen increased by 16.0mg / L ~ (-1), and the respiration at night was greater than that of photosynthesis. The pH decreases 7.57% and the dissolved oxygen decreases 2.5 mg 路L ~ (-1) 路L ~ (-1) 路L ~ (-1) ~ (-1) 路L ~ (-1); In sediment, with the increase of sediment depth, the pH of dissolved oxygen (DO) Eh decreased, but the decrease of cyanobacteria group was faster. 2) the condition of simulating the outbreak of cyanobacteria in laboratory. In situ monitoring of the content of available Fe2 and the release flux of Fe2 in sediment were performed by ZrO-ChelexDGT and other techniques. The effect of cyanobacteria Shui Hua on iron content in sediments was studied. The Fe2 content in overlying water was very low, and the Fe2 content in 0.5 cm interfacial interstitial water increased significantly. The photosynthetic pH of cyanobacteria increased and the soluble Fe2 released from cyanobacteria was partly absorbed by cyanobacteria for their growth. From the 5th day, the flux of cyanobacteria increased significantly. The content of Fe2 in the overlying water was very low, and the Fe2 released gradually from 0-20mm to 20mm, with the increase of depth. The effective Fe2 content decreased gradually. 3) the condition of simulated cyanobacteria outbreak was simulated in laboratory. The gap water was monitored in situ by using ZrO-ChelexDGT and other techniques. The release mechanism of phosphorus in sediments during the period of Shui Hua was studied. The photosynthesis of cyanobacteria increased the pH value of do in the overlying water during the day and pH at night. The decrease of do increased the release of PO4- from sediments, and the direct adsorption of P by cyanobacteria decreased the concentration of P in interstitial water after 5 days. The increase of OH- no longer promoted the release of PO4- from sediments. The release of P in sediment was mainly controlled by do and the degradation of cyanobacteria. The concentration of nitrate and ammonia in the interstitial water was higher than that in the overlying water. There is a molecular diffusion from high concentration to low concentration. The change trend of nitrate nitrogen and ammonia nitrogen content in overlying water is the same, and it decreases from the first day to the fifth day. The main form of dissolved nitrogen in interstitial water is ammonia nitrogen, and the change of nitrate nitrogen in sediment at different depths is the same as that of ammonia nitrogen, which decreases first and then increases.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X524

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